Revert "TST: Log scale on bar chart hides bars GH3247" mpl 1.2.1 regression

This reverts commit 682b39ed851c272aef4872dc59571c4266cd2ff4.
ENH: In HDFStore, add select_column method, deprecate unique method
DOC: cookbook example
Merge pull request #3256 from jreback/hdf_column

ENH: In HDFStore, add select_column method, deprecate unique method
BLD: test_perf, set cpu affinity and do a gc collect between vbs, in --head mode
BLD: test_perf, add burn-in, warn if 'affinity' missing, transpose running order in --head